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Inhibitory neuron migration and IPL formation in the developing zebrafish retina.

Chow RW, Almeida AD, Randlett O, Norden C, Harris WA - Development (2015)

Bottom Line: All RINs then transition to a less directionally persistent multipolar phase of migration.Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.

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Basally migrating RINs in apical regions of the retina appear bipolar. (A) Selected frames from a movie of a Ptf1a:DsRed retina starting at ∼45 hpf. Images are shown as maximum intensity z-projections. At 0 min, tips of RIN apical processes (arrowheads) are seen to be attached to the apical surface of the retina (top dashed green line). At 540 min, when dACs (blue arrows) can be seen to separate from the main body of RINs in the middle of the retina, multipolar RINs, presumably HCs, can be seen migrating towards the OPL (orange arrows). (B) Selected time frames from a movie of Ptf1a:DsRed cells transplanted into a WT embryo starting at ∼45 hpf. Blue arrowheads indicate a RIN that transitions from bipolar to multipolar morphology. AS, apical surface; BS, basal surface.
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DEV122473F1: Basally migrating RINs in apical regions of the retina appear bipolar. (A) Selected frames from a movie of a Ptf1a:DsRed retina starting at ∼45 hpf. Images are shown as maximum intensity z-projections. At 0 min, tips of RIN apical processes (arrowheads) are seen to be attached to the apical surface of the retina (top dashed green line). At 540 min, when dACs (blue arrows) can be seen to separate from the main body of RINs in the middle of the retina, multipolar RINs, presumably HCs, can be seen migrating towards the OPL (orange arrows). (B) Selected time frames from a movie of Ptf1a:DsRed cells transplanted into a WT embryo starting at ∼45 hpf. Blue arrowheads indicate a RIN that transitions from bipolar to multipolar morphology. AS, apical surface; BS, basal surface.

Mentions: To visualize RIN migration, we made use of a transgenic zebrafish line in which the promoter of the gene that encodes the basic helix-loop-helix (bHLH) transcription factor Ptf1a drives the expression of DsRed in RINs (Jusuf and Harris, 2009). This allowed us to follow several Ptf1a+ cells located in apical parts of the retina (Fig. 1A; supplementary material Movie 1). All of these cells exhibited elongated bipolar morphologies as they migrated basally towards the centre of the retina (Fig. 1A, 0 min). Moreover, it became clear that most of these cells retracted their apical processes only after they reached the middle of the retina (Fig. 1A, 150 min). Multipolar Ptf1a+ cells in the apical part of the INL (i.e. HCs) became apparent only later (Fig. 1A, 540 min). These observations suggested that many RINs begin their migration in a bipolar mode before switching to a multipolar morphology.Fig. 1.


Inhibitory neuron migration and IPL formation in the developing zebrafish retina.

Chow RW, Almeida AD, Randlett O, Norden C, Harris WA - Development (2015)

Basally migrating RINs in apical regions of the retina appear bipolar. (A) Selected frames from a movie of a Ptf1a:DsRed retina starting at ∼45 hpf. Images are shown as maximum intensity z-projections. At 0 min, tips of RIN apical processes (arrowheads) are seen to be attached to the apical surface of the retina (top dashed green line). At 540 min, when dACs (blue arrows) can be seen to separate from the main body of RINs in the middle of the retina, multipolar RINs, presumably HCs, can be seen migrating towards the OPL (orange arrows). (B) Selected time frames from a movie of Ptf1a:DsRed cells transplanted into a WT embryo starting at ∼45 hpf. Blue arrowheads indicate a RIN that transitions from bipolar to multipolar morphology. AS, apical surface; BS, basal surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4529032&req=5

DEV122473F1: Basally migrating RINs in apical regions of the retina appear bipolar. (A) Selected frames from a movie of a Ptf1a:DsRed retina starting at ∼45 hpf. Images are shown as maximum intensity z-projections. At 0 min, tips of RIN apical processes (arrowheads) are seen to be attached to the apical surface of the retina (top dashed green line). At 540 min, when dACs (blue arrows) can be seen to separate from the main body of RINs in the middle of the retina, multipolar RINs, presumably HCs, can be seen migrating towards the OPL (orange arrows). (B) Selected time frames from a movie of Ptf1a:DsRed cells transplanted into a WT embryo starting at ∼45 hpf. Blue arrowheads indicate a RIN that transitions from bipolar to multipolar morphology. AS, apical surface; BS, basal surface.
Mentions: To visualize RIN migration, we made use of a transgenic zebrafish line in which the promoter of the gene that encodes the basic helix-loop-helix (bHLH) transcription factor Ptf1a drives the expression of DsRed in RINs (Jusuf and Harris, 2009). This allowed us to follow several Ptf1a+ cells located in apical parts of the retina (Fig. 1A; supplementary material Movie 1). All of these cells exhibited elongated bipolar morphologies as they migrated basally towards the centre of the retina (Fig. 1A, 0 min). Moreover, it became clear that most of these cells retracted their apical processes only after they reached the middle of the retina (Fig. 1A, 150 min). Multipolar Ptf1a+ cells in the apical part of the INL (i.e. HCs) became apparent only later (Fig. 1A, 540 min). These observations suggested that many RINs begin their migration in a bipolar mode before switching to a multipolar morphology.Fig. 1.

Bottom Line: All RINs then transition to a less directionally persistent multipolar phase of migration.Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.

Show MeSH